There is known a technology of using one and the same personal telephone number recognizable in different telecommunications networks. For example, EP 0738093 A2 (to TELIA AB), which is incorporated herein by reference, describes the technology where one telephone number is associated with a subscriber in various different communications networks. A condition for using this personal number is a central network node located at or being in communication with the mentioned different networks, preferably PSTN, ISDN, or mobile networks such as GSM and NMT (Nordic Mobile Telephony). The central network node does not influence network functions, numbering schemes and terminals in these networks. When a call is directed to a subscriber associated with any of the mentioned telecommunications network or utilizing a cordless access system, the call (independent of which telecommunications network it emanates) is connected to this central network node which converts the received personal number to the specific number corresponding to the communications network at which the subscriber has registered himself/herself. Upon that conversion, the network node connects the call to the current access point which corresponds to the specific number.
Also, there is known a U.S. Pat. No. 6,301,474 (to Openwave Technologies Inc.) which is incorporated hereby by reference, describing a mobility extended telecommunication application. The technology comprises an integrated wireless and wireline network with central control, which has a programmed interface to translate between the different protocols of the wireless and the wireline networks to allow for automatic redirection of a new incoming call, that is about to be established, between a telephone device of the wireless network and a telephone device of the wireline network.
EP 0763 308 B1 describes an arrangement for interconnecting a cellular communication system and a cordless access system. The interconnecting arrangement comprises an interworking function (IWF) which via an existing interface of the cellular system is connected to a Mobile Switching Center thereof and which via another interface is connected to a cordless access system. However, some of the major drawbacks of the disclosure in this EP patent are that the interworking function is workable only with cordless devices, and that it requires a DECT fixed part associated with each of the users of this solution.
The services proposed in the above patent publications are quite advanced. However, there are quite a few drawbacks to the methods described. Every user who intensively uses the phone, often encounters the situation when a conversation starts while using a fixed phone (cordless or not) but, since the user must leave the premises, the conversation has to be stopped and, upon redialing, to be continued from a mobile phone. The users are also familiar with an opposite situation, when a communication session starts at a mobile phone and after a period of time could have been continued at a fixed or cordless phone (e.g. while obtaining a higher quality of service and/or while using more comfortable appliances at the premises), but the cumbersome operation of disconnecting and re-connecting prevents the user from making that switch.
There are also many other situations where a user of a mobile network (who is also a user of a non-mobile network) would be interested of transparently using facilities of the non-mobile network and facilities of the mobile network whenever desired.